In the various Sonic the Hedgehog continuities, there are several instances where the characters encounter extraterrestrial life.
The Marmolimians are aliens that hail from the Planet Marmolim. They resemble short creatures with heads that are either round, shaped like a Chao's head or stretched. They also have small tufts of hair on their heads. The Marmolimians are apparently religious, frequently using magic-based charms in love and fortune-telling. Their only appearance was in the 69th episode of Sonic X, where they somewhat helpedTails and Cosmo to fall in love with each other. Marmolimians possess ships that resemble meteors. They also use a coin-based currency called Fleebos. Four Marmolimians named Lu, Leela, Momo and Gana (the latter is the spiritual elder) formed the crew of the ship that they owned.
Sonic the Hedgehog comic series